Bred
Vectors (BVs) are computed as follows:

1)Start with an arbitrary initial perturbation of size **A** defined with

an
arbitrary norm. This initialization step is executed only once. The size is

essentially
the only tunable parameter of breeding.

2)
Add the perturbation to the basic solution, integrate the perturbed initial

condition
with the nonlinear model, and subtract the original unperturbed

solution
from the perturbed nonlinear integration:

3)
Divide the perturbation by the measured amplification factor so that

its
size remains equal to **A**: